static void dns_handle_local() {
struct sockaddr *src_addr = malloc(sizeof(struct sockaddr));
socklen_t src_addrlen = sizeof(struct sockaddr);
uint16_t query_id;
ssize_t len;
int i;
const char *question_hostname;
ns_msg msg;
len = recvfrom(local_sock, global_buf, BUF_SIZE, 0, src_addr, &src_addrlen);
if (len > 0) {
if (ns_initparse((const u_char *)global_buf, len, &msg) < 0) {
ERR("ns_initparse");
free(src_addr);
return;
}
// parse DNS query id
// TODO generate id for each request to avoid conflicts
query_id = ns_msg_id(msg);
question_hostname = hostname_from_question(msg);
LOG("request %s\n", question_hostname);
id_addr_t id_addr;
id_addr.id = query_id;
id_addr.addr = src_addr;
id_addr.addrlen = src_addrlen;
queue_add(id_addr);
for (i = 0; i < dns_servers_len; i++) {
if (-1 == sendto(remote_sock, global_buf, len, 0,
dns_server_addrs[i].addr, dns_server_addrs[i].addrlen))
ERR("sendto");
}
}
else
ERR("recvfrom");
}
static void dns_handle_remote() {
struct sockaddr *src_addr = malloc(sizeof(struct sockaddr));
socklen_t src_len = sizeof(struct sockaddr);
uint16_t query_id;
ssize_t len;
const char *question_hostname;
int r;
ns_msg msg;
len = recvfrom(remote_sock, global_buf, BUF_SIZE, 0, src_addr, &src_len);
if (len > 0) {
if (ns_initparse((const u_char *)global_buf, len, &msg) < 0) {
ERR("ns_initparse");
free(src_addr);
return;
}
// parse DNS query id
query_id = ns_msg_id(msg);
question_hostname = hostname_from_question(msg);
if (question_hostname) {
LOG("response %s from %s:%d - ", question_hostname,
inet_ntoa(((struct sockaddr_in *)src_addr)->sin_addr),
htons(((struct sockaddr_in *)src_addr)->sin_port));
}
id_addr_t *id_addr = queue_lookup(query_id);
if (id_addr) {
id_addr->addr->sa_family = AF_INET;
uint16_t ns_old_id = htons(id_addr->old_id);
memcpy(global_buf, &ns_old_id, 2);
r = should_filter_query(msg, ((struct sockaddr_in *)src_addr)->sin_addr);
if (r == 0) {
if (verbose)
printf("pass\n");
if (-1 == sendto(local_sock, global_buf, len, 0, id_addr->addr,
id_addr->addrlen))
ERR("sendto");
} else if (r == -1) {
schedule_delay(query_id, global_buf, len, id_addr->addr,
id_addr->addrlen);
if (verbose)
printf("delay\n");
} else {
if (verbose)
printf("filter\n");
}
} else {
if (verbose)
printf("skip\n");
}
free(src_addr);
}
else
ERR("recvfrom");
}
int
filter_query(uint8_t *buf, int buflen) {
ns_msg msg;
if (local_ns_initparse(buf, buflen, &msg) < 0) {
logger_log(LOG_ERR, "local_ns_initparse");
return -1;
} else {
int i;
const char *host = hostname_from_question(msg);
for (i = 0; i < black_list.elements; i++) {
int rc = domain_match(host, black_list.domains[i]);
if (rc) {
logger_log(LOG_INFO, "request %s", host);
return 0;
}
}
}
return 1;
}
static void dns_handle_local() {
struct sockaddr *src_addr = malloc(sizeof(struct sockaddr));
socklen_t src_addrlen = sizeof(struct sockaddr);
uint16_t query_id;
ssize_t len;
int i;
int sended = 0;
const char *question_hostname;
ns_msg msg;
len = recvfrom(local_sock, global_buf, BUF_SIZE, 0, src_addr, &src_addrlen);
if (len > 0) {
if (ns_initparse((const u_char *)global_buf, len, &msg) < 0) {
ERR("ns_initparse");
free(src_addr);
return;
}
// parse DNS query id
// TODO generate id for each request to avoid conflicts
query_id = ns_msg_id(msg);
question_hostname = hostname_from_question(msg);
LOG("request %s\n", question_hostname);
// assign a new id
uint16_t new_id;
do {
struct timeval tv;
gettimeofday(&tv, 0);
int randombits = (tv.tv_sec << 8) ^ tv.tv_usec;
new_id = randombits & 0xffff;
} while (queue_lookup(new_id));
uint16_t ns_new_id = htons(new_id);
memcpy(global_buf, &ns_new_id, 2);
id_addr_t id_addr;
id_addr.id = new_id;
id_addr.old_id = query_id;
id_addr.addr = src_addr;
id_addr.addrlen = src_addrlen;
queue_add(id_addr);
if (compression) {
if (len > 16) {
size_t off = 12;
int ended = 0;
while (off < len - 4) {
if (global_buf[off] & 0xc0)
break;
if (global_buf[off] == 0) {
ended = 1;
off ++;
break;
}
off += 1 + global_buf[off];
}
if (ended) {
memcpy(compression_buf, global_buf, off-1);
memcpy(compression_buf + off + 1, global_buf + off, len - off);
compression_buf[off-1] = '\xc0';
compression_buf[off] = '\x04';
for (i = 0; i < has_chn_dns; i++) {
if (-1 == sendto(remote_sock, global_buf, len, 0,
dns_server_addrs[i].addr,
dns_server_addrs[i].addrlen))
ERR("sendto");
}
for (i = has_chn_dns; i < dns_servers_len; i++) {
if (-1 == sendto(remote_sock, compression_buf, len + 1, 0,
dns_server_addrs[i].addr,
dns_server_addrs[i].addrlen))
ERR("sendto");
sended = 1;
}
}
}
}
if (!sended) {
for (i = 0; i < dns_servers_len; i++) {
if (-1 == sendto(remote_sock, global_buf, len, 0,
dns_server_addrs[i].addr,
dns_server_addrs[i].addrlen))
ERR("sendto");
}
}
}
else
ERR("recvfrom");
}
